EmulatorJS vs RePlayOS

EmulatorJS is a free, open-source frontend for RetroArch that lets a site owner embed an emulator in a web page. The project provides a code generator, and says the resulting embed can be added with a few lines of code. EmulatorJS uses RetroArch’s libretro cores to run games. Its supported systems documentation includes NES, Nintendo 64, PlayStation, PSP, Sega systems, and Commodore systems, though the project warns that this list may be out of date. Built-in options allow customization, and multiple languages are supported. The project describes EmulatorJS as a library or plugin rather than a standalone website, and it does not provide a Docker container. A public CDN offers paths labeled stable, latest, and nightly. The listed platforms are web, Android, iOS, and self-hosted. Pages must be served through a web server; opening an HTML file directly is unsupported. Threaded cores may improve performance, but need SharedArrayBuffer enabled through COOP and COEP response headers. The 4.3.0-pre release is marked as a prerelease and is discouraged for production use where stability is needed.

RePlayOS is a Linux distribution for emulating classic game consoles, arcade machines, and computers through a streamlined libretro frontend. It is built around Raspberry Pi hardware, with listed support for Zero 2, 3A/B/B+, 4B, and 5B models, and works with LCD and CRT screens. Its DynaRes display engine supports native CRT timings, timing changes, CRT profiles, dual-screen modes, and LCD operation at game refresh rates. The system supports more than 700 controllers and up to six players, plus RetroAchievements in compatible cores and games. Replay Control is a companion web app for browsing games, launching them on a TV, managing favorites, and configuring the system over a local network. Compatible cores can use Link Play multiplayer over that network. Alpha Player handles audio and video files, with Raspberry Pi 5 recommended for movies. A small HTTP JSON API provides local or LAN control when enabled, but uses plain HTTP. The public version is free; the frontend is proprietary, with restrictions on modification, standalone redistribution, and unauthorized commercial use.